Update CHANGELOG.md (Azure#39343)

Author: nisha-bhatia

sdk/monitor/Azure.Monitor.Query/CHANGELOG.md

@@ -1,17 +1,11 @@
 # Release History
 
-## 1.3.0-beta.1 (Unreleased)
+## 1.3.0-beta.1 (2023-10-18)
 
 ### Features Added
 - Added the `MetricsBatchQueryClient` client to support batch querying of metrics.
 - Added `QueryBatch` and `QueryBatchAsync` methods to `MetricsBatchQueryClient`
 
-### Breaking Changes
-
-### Bugs Fixed
-
-### Other Changes
-
 ## 1.2.0 (2023-05-22)
 
 ### Bugs Fixed